In recent years, charging/discharging devices that charge a storage battery mounted on an electric car and supply power accumulated in the storage battery to household loads (such as an air conditioner and a refrigerator) have attracted attention along with the popularization of electric cars (for example, Patent Literature 1 mentioned below).
A charging/discharging cable connected to the charging/discharging device is provided with a charging/discharging connector (hereinafter, “connector”) that can be attached to or detached from a connector connection port of an electric car, and the storage battery mounted on the electric car is electrically connected to the charging/discharging device via the connector. Because the voltage of the storage battery reaches several hundred volts, if an operator touches a connector electrode or the like during energization, there is a risk that the operator receives an electric shock. Therefore, when the connector is connected to the connector connection port, a predetermined communication is performed between the charging/discharging device and the vehicle controller in the electric car, and after safety is confirmed, charging/discharging is performed. A mechanical lock mechanism (a connector disconnection prevention mechanism) is provided to the connector. For example, when a charging/discharging starting operation is performed in the charging/discharging device, a lock-actuator drive signal (a signal for operating the lock mechanism) is transmitted to the connector from the charging/discharging device to actuate the lock mechanism provided to the connector, thereby maintaining the mechanical connection state between the connector connection port and the connector.